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Today on Animal Fact Files we’re discussing hagfish. You can subscribe to the channel to stay up to date on new animal fact releases! Hagfish are kind of an enigma of the animal kingdom. They’re technically classified as fish meaning they’re also considered vertebrates, but they are completely lacking vertebrae which is kind of the number one qualifier for vertebrate classification. They do have a partial skull and the foundation of vertebrae, and they have a skeleton made up of cartilage like a shark, but they don’t have a jaw. To keep things simple, we’re just going to throw them in the fish playlist because, as it stands, they’re still technically called fish… sort of.

Hagfish are often referred to as primitive fish because of their unique features. This is pretty apt because they’ve been around for more than 300 million years, and as far as we can tell they’ve barely changed in that time. There are somewhere around 80 species of hagfish swimming in all the world’s oceans as well as many of the large seas. They live anywhere from shallow areas to over a mile (1.61km) below the water’s surface sometimes living in burrows. To see a hagfish one may not immediately think they are fish. They look more like eels and are often referred to as slime eels which we’ll discuss in just a moment. They have no fins and a single nostril, their mouth looks like something only Lovecraft could concoct, and their eyes are covered by their skin to the point that the eyes are basically useless.

Hagfish also have tentacles on the front of their face that aid in sensory perception. Hagfish average two feet (60.96cm) in length and come in colors of pinkish grey and reddish brown. When attacked by a predator, a hagfish will release a slime-like substance from pores found along the length of their body. When this substance comes in contact with the surrounding water, it expands in size. This leaves any predator with a mouthful of goo and no hagfish. The goo can clog a predator’s gills which gives the hagfish ample time to escape. Hagfish don’t really have to worry about sliming themselves, either because they are able to tie themselves into a knot which they can contort down the length of their body to push off any excess slime. They’re also able to sneeze out and goo from their nostril and then close their nostril so no goo gets in. Primitive, maybe, but incompetent, definitely not. Of course, this slimy squirting doesn’t stop a predator from actually biting a hagfish, so they’ve developed to have extremely loose skin. A hagfish’s skin is attached to only a few points on it’s body, so when something bites down, the skin just slides around, making the predator’s teeth slide with it. I’m thinking the best adjective to describe a hagfish is slippery. Just sayin’! Hagfish are eaten by some animals, however, and those include fish who can get through the slime, seals, and even birds.

Some people think hagfish are disgusting because of the way they eat, but I think it’s kind of disgusting that people eat hagfish, so it’s all a matter of perspective. Hagfish generally dine on dead animals that have sunk to the seafloor. They will burrow into a carcass and eat it from the inside out. This is done using that specially designed mouth we mentioned earlier. Technically speaking, hagfish don’t have teeth, but try telling that the dying fish they’re burrowing into. Hagfish have sharp teeth-like structures atop plates that are on what it kind of like their tongue. They’ll pinch at flesh by pushing these plates together and tear a meal apart. In order to help keep their catch to themselves, hagfish will coat their meal in that same defensive slime. When they aren’t eating dead things, they also consume crustaceans. Of course, they have super slow metabolisms so they can go more than half a year without eating. I can’t even imagine Chester going more than half a day without eating. I think the world would implode.

We really aren’t sure how hagfish mate. Some think they release eggs and sperm into the water column like many fish species, others think they could have internal fertilization; some say they’re distinctly split sexually, and others claim that they can change sex year by year. What we do know is that their eggs are rather large as compared to other fish eggs, so females don’t produce many at one time, and they hatch fully developed looking just like miniature versions of their parents.

Some other crazy things to know about hagfish are that they caused a massive traffic jam with their slime in Oregon back in 2017. There’s been one observed attached to the blowhole of a bottlenose dolphin. Their three hearts don’t need oxygen to work for hours on end. And if you ever see something labelled as “eel skin” you can almost be sure it’s actually hagfish. Talk about some false marketing!

For more information on hagfish, check out the links in the description. Let us know what you think of this strange creatures in the comments. Give a thumbs up if you enjoyed the video, and we’ll see you next time on Animal Fact Files.